api 2i.pdf

In-Service Inspection of MooringHardware for Floating Drilling Units

API RECOMMENDED PRACTICE 2ISECOND EDITION, NOVEMBER 1996

EFFECTIVE DATE: FEBRUARY 1, 1997

COPYRIGHT 2000 American Petroleum InstituteInformation Handling Services, 2000COPYRIGHT 2000 American Petroleum InstituteInformation Handling Services, 2000

In-Service Inspection of MooringHardware for Floating Drilling Units

Exploration and Production Department

API RECOMMENDED PRACTICE 2ISECOND EDITION, NOVEMBER 1996

EFFECTIVE DATE: FEBRUARY 1, 1997


SPECIAL NOTES

API publications necessarily address problems of a general nature. With respect to partic-ular circumstances, local, state, and federal laws and regulations should be reviewed.

API is not undertaking to meet the duties of employers, manufacturers, or suppliers towarn and properly train and equip their employees, and others exposed, concerning healthand safety risks and precautions, nor undertaking their obligations under local, state, orfederal laws.

Information concerning safety and health risks and proper precautions with respect to par-ticular materials and conditions should be obtained from the employer, the manufacturer orsupplier of that material, or the material safety data sheet.

Nothing contained in any API publication is to be construed as granting any right, byimplication or otherwise, for the manufacture, sale, or use of any method, apparatus, or prod-uct covered by letters patent. Neither should anything contained in the publication be con-strued as insuring anyone against liability for infringement of letters patent.

Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at least everyfive years. Sometimes a one-time extension of up to two years will be added to this reviewcycle. This publication will no longer be in effect five years after its publication date as anoperative API standard or, where an extension has been granted, upon republication. Statusof the publication can be ascertained from the API Authoring Department [telephone (202)682-8000]. A catalog of API publications and materials is published annually and updatedquarterly by API, 1220 L Street, N.W., Washington, D.C. 20005.

This document was produced under API standardization procedures that ensure appropri-ate notification and participation in the developmental process and is designated as an APIstandard. Questions concerning the interpretation of the content of this standard or com-ments and questions concerning the procedures under which this standard was developedshould be directed in writing to the director of the Authoring Department (shown on the titlepage of this document), American Petroleum Institute, 1220 L Street, N.W., Washington,D.C. 20005. Requests for permission to reproduce or translate all or any part of the materialpublished herein should also be addressed to the director.

API standards are published to facilitate the broad availability of proven, sound engineer-ing and operating practices. These standards are not intended to obviate the need for apply-ing sound engineering judgment regarding when and where these standards should beutilized. The formulation and publication of API standards is not intended in any way toinhibit anyone from using any other practices.

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All rights reserved. No part of this work may be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise,

without prior written permission from the publisher. Contact the Publisher, API Publishing Services, 1220 L Street, N.W., Washington, D.C. 20005.

Copyright © 1996 American Petroleum Institute


iii

FOREWORD

API publications may be used by anyone desiring to do so. Every effort has been made bythe Institute to assure the accuracy and reliability of the data contained in them; however, theInstitute makes no representation, warranty, or guarantee in connection with this publicationand hereby expressly disclaims any liability or responsibility for loss or damage resultingfrom its use or for the violation of any federal, state, or municipal regulation with which thispublication may conflict.

Suggested revisions are invited and should be submitted to the director of the Explora-tion and Production Department, American Petroleum Institute, 1220 L Street, N.W.,Washington, D.C. 20005.


v

CONTENTS

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1 SCOPE

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 REFERENCES

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

3 GUIDELINES FOR IN-SERVICE INSPECTIONOF MOORING CHAIN AND ANCHOR JEWELRY

. . . . . . . . . . . . . . . . . 13.1 Common Problems with Used Chain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2 Recommended Inspection Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

3.2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.2.2 Dockside Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.2.3 Offshore Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3.3 Recommended Inspection Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.3.1 Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.3.2 Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43.3.3 Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.3.4 Cleaning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.3.5 Inspection Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.4 Guidelines for Rejecting Chain Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73.5 Guidelines for Chain Repair, Removal, and Replacement. . . . . . . . . . . . . . . . . . . . 83.6 Recommended Inspection Schedule. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4 GUIDELINES FOR IN-SERVICE INSPECTION OF MOORING-WIRE ROPE AND ANCHOR HANDLING EQUIPMENT

. . . . . . . . . . . 94.1 Common Problems with Used Mooring-Wire Rope . . . . . . . . . . . . . . . . . . . . . . . . 9

4.1.1 Broken Wires. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94.1.2 Change in Rope Diameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94.1.3 Wear. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94.1.4 Corrosion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94.1.5 Loss of Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.1.6 Deformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124.1.7 Thermal Damage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.2 Recommended Inspection Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134.2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134.2.2 Inspection During Anchor Retrieval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134.2.3 Dockside Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.3 Recommended Inspection Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144.3.1 Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144.3.2 Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144.3.3 Length of Rope Covered by Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144.3.4 Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.3.5 Cleaning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.3.6 Inspection Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.4 Guidelines for Rejecting Wire Rope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174.4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174.4.2 Distributed Crown Broken Wires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174.4.3 Grouped Brown Broken Wires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184.4.4 Valley Broken Wires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184.4.5 Broken Wires at Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184.4.6 Wear and Stretch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184.4.7 Internal Corrosion and Wear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18


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4.4.8 Deformations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184.4.9 Core Deterioration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194.4.10 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.5 Recommended Inspection Schedule. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194.6 Recommendations for Proper Use and Maintenance

of Mooring-Wire Rope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194.7 Inspection of Anchor-Handling Equipment and Termination

of Pendant Wire Rope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194.7.1 Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194.7.2 Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

APPENDIX A—RECOMMENDED PROCEDURES FORMAGNETIC PARTICLE INSPECTION (MPI)

. . . . . . . . 21

APPENDIX B—SOCKETING

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FIGURES

Figure 1—Typical Chain Stud Problems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Figure 2—Chain Diameter Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Figure 3—Dockside Inspection Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Figure 4—Offshore Inspection Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Figure 5—Chain Length Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Figure 6—Inspection of Anchor Jewelry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Figure 7—Discard Criterion for Bent Links . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Figure 8—Examples of Severely Loose Studs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Figure 9—Examples of Distributed Crown Wire Breaks . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Figure 10—Typical Wire Fractures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Figure 11—Locally Grouped Broken Wires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Figure 12—Local Decrease in Rope Diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Figure 13—Progression of Wear in Wire Rope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Figure 14—Wire Rope with Heavy External Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Figure 15—Progression of External Corrosion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Figure 16—Wear of Internal Wires Caused by Lack of Lubricant Between Wires . . . . . . 13Figure 17—Effect of Internal Lubrication on Wire Rope . . . . . . . . . . . . . . . . . . . . . . . . . . 13Figure 18—Kink and Bend of Wire Rope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Figure 19—Deformation Caused by Improper Drum Winding . . . . . . . . . . . . . . . . . . . . . 14Figure 20—Wire Rope Inspection with the Assistance of a Workboat. . . . . . . . . . . . . . . . 15Figure 21—Lay Length and Diameter Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Figure 22—Internal Inspection of Wire Rope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Figure 23—Common Rope Constructions for Mooring Applications . . . . . . . . . . . . . . . . 18Figure 24—Acceptable Terminations for Pendant Wire Rope . . . . . . . . . . . . . . . . . . . . . . 20Figure B-1—Zinc-poured Socketing Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

TABLES

Table 1—Upper Limit of Length Over Five Linksand Length of Individual Link for Used Chain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Table 2—Chain Inspection Intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Table 3—Criteria for Crown Broken Wires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Table 4—Rope Inspection Intervals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Table 5—Minimum Sheave-Groove and Drum-Groove Dimensions . . . . . . . . . . . . . . . . 20

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1

In-Service Inspection of Mooring Hardware for Floating Drilling Units

1 SCOPE

This document provides comprehensive guidelines forinspecting catenary mooring components of floating drillingunits. It was developed in response to the need for an industrystandard for such inspections. Some discard criteria for usedchain and wire rope have been established and used by somemanufacturers, regulatory bodies, operators, and drilling con-tractors. However, these criteria vary, widely and most ofthem cannot be applied directly to the mooring of floatingdrilling units. To ensure good mooring inspection quality andto form an industry agreement on discard criteria, this recom-mended practice was developed.

The need for rigorous, effective inspection of mooringhardware is apparent because most of the mooring failuresinvolved faulty mooring components including corroded orphysically damaged wire-rope or chain, defective connectinglinks, or mooring hardware of inferior quality.

This document should be useful to engineers and operatingpersonnel concerned with the following:

a. Planning a mooring inspection.b. Conducting or supervising a mooring inspection.c. Deciding whether to reject, repair, or replace mooringhardware.d. Communicating with others concerning acceptable moor-ing hardware.

This document compiles factors that are best understoodand can be quantified at this time. The information in thisdocument will be updated after further experience and knowl-edge are gained. Accordingly, we encourage comments andsuggestions toward broadening and refining these guidelines.

Although this recommended practice was developed formoorings of floating drilling units, some of the guidelinesmay be applicable to moorings of other floating vessels suchas floating production platforms, pipe-laying barges, and con-struction barges. The applicability of this document to otherfloating vessels is left to the discretion of the user.

2 REFERENCES

The most recent editions or revisions of the following stan-dards are referenced in this publication:

AISI

1

Wire Rope User’s Manual

ASTM

2

B6-87

Specification for Zinc

E709

Practice for Magnetic Particle Examination

ISO

3

Std 4309

Cranes—Wire Ropes—Code of Practice forExamination and Discard

3 GUIDELINES FOR IN-SERVICE INSPECTION OF MOORING CHAIN AND ANCHOR JEWELRY

3.1 Common Problems with Used Chain

The rough treatment to which mooring chain is exposedcan lead to various chain problems. Eight such common prob-lems for which inspectors should be alert are described in3.1.1 to 3.1.8.

3.1.1

Missing studs. A chain link without a stud may sig-nificantly increase the possibility of link failure; high bendingstresses and low fatigue life in links are predictable conse-quences of missing studs.

3.1.2

Bent links. A bent link is the result of chain-handlingabuse. The link may have been excessively torqued when tra-versing a sharp, curved surface; or the chain may havejumped over the wildcat, making point contacts between thelink and the wildcat. Jumping of chain over the wildcat isusually caused by a worn wildcat, by chain dimensions out oftolerance, or by too abrupt braking of fast moving chain.

3.1.3

Corrosion. Excessive corrosion increases the possi-bility of chain failure from corrosion fatigue or overloadingdue to reduced cross-sectional area.

3.1.4

Sharp gouges. Physical damage to the chain surface(such as cuts and gouges) raises stress and promotes fatiguefailure.

3.1.5

Loose studs. Loose studs caused by abusive handlingor by excessive corrosion between the link and the stud allowexcessive stretching of chain, causing higher bending stressesin the chain. A typical loose stud is shown in Figure 1, Part a.

3.1.6

Cracks. Surface cracks, flash-weld cracks, and stud-weld cracks may propagate under cyclic loading, resulting inpremature chain failure. A typical stud-weld crack is shownin Figure 1, Part b.

3.1.7

Wear. Wear between links in the grip area andbetween links and the wildcat (see Figure 2, Part b) reducesthe chain diameter. The diameter reduction decreases theload-carrying capacity of the chain and invites failure.

1

.

American Iron and Steel Institute, 1101 17th Street, N.W., 13th Floor, Washington, D.C. 20036-4700.

2

.

American Society for Testing and Materials, 100 Bar Harbor Drive, WestConshohocken, Pennsylvania 19428.

3

.

International Organization for Standardization. ISO publications are available from the American National Standards Institute, 11 West 42nd Street, New York, New York 10036.


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3.1.8

Elongation. Excessive permanent elongation maycause the chain to function improperly in the wildcat, result-ing in bending and wear of the links. Wear in the grip area ofthe chain and working loads in excess of the original proofload will result in a permanent elongation of the chain.

3.2 Recommended Inspection Method

3.2.1 GENERAL

Chain installed on mobile offshore drilling units can beinspected by the two methods in 3.2.2 and 3.2.3.

3.2.2 DOCKSIDE INSPECTION

As shown in Figure 3, the drilling vessel is taken into adock, and the chain is laid out on a dry surface for inspec-tion. Normally such chain inspection is carried out in con-

A LOOSE STUD IN 3-INCH ORQ CHAIN

B. CRACKED STUD WELD IN 3-INCH ORQ CHAIN

Figure 1—Typical Chain Stud Problems

Figure 2—Chain Diameter Measurement

A. DIAMETERS IN TWO PERPENDICULAR DIRECTIONS

B. AREAS OF HEAVY WEAR

C. TWO DIAMETER MEASUREMENTS (OFFSHORE INSPECTION METHOD)

D. DIAMETER CALIPER

E. GO-NO-GO GAUGE


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junction with other work such as major structural repair orspecial survey.

In this manner the entire chain can be thoroughly cleanedand carefully inspected, and the connecting links and anchorshackles can be examined by magnetic particle inspection(MPI). Since the chain is not under tension, the chain diame-ter in the grip area can be readily measured. However, themeasurement of a length of five links, which should beaccomplished under tension, would be inaccurate.

3.2.3 OFFSHORE INSPECTION

As shown in Figure 4, the drilling vessel stays offshore,and the chain is inspected with the assistance of a workboat.The chain in the chain locker should be paid out fully andthen examined by an inspector standing close to the windlasswhile the chain is slowly taken back into the chain locker. Atthe same time, the workboat picks up the anchor and movesslowly toward the vessel.

The advantage of this method is that it requires no dockfacilities. The inspection can be performed whenever a workboat is available or in conjunction with anchor retrieval. How-ever, this method has the following disadvantages:

a. Inspecting the last approximate 200 feet of chain is diffi-cult. However, if the chain can be reached by a crane, anddeck space on the drilling vessel is available, the anchor andthe last portion of chain can be picked up by the crane andlaid on the deck for inspection. Otherwise, the anchor and thelast portion of chain can be brought on board the work boatand inspected there. b. Inspection of connecting links by MPI is suggested in 3.3.However, MPI is difficult and time consuming with the off-shore inspection method; it could substantially increase work-boat waiting time and delay the rig moving schedule. Thisproblem can be alleviated by exchanging the connecting linksin the chain with spare connecting links that have been exam-ined by MPI prior to chain inspection.

3.3 Recommended Inspection Procedure

3.3.1 PERSONNEL

3.3.1.1 Dockside Inspection Method

The following list describes personnel and duties for thedockside inspection method:

a. The chief inspector coordinates the work among inspec-tion personnel, performs visual inspection, performs mea-surements, and rejects or accepts damaged links.b. The assistant keeps inspection records and assists withmeasurements.c. The MPI inspector performs MPI on connecting links andanchor jewelry.

Figure 3—Dockside Inspection Method


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d. Roughnecks clean chain, grind out surface defects, dis-mantle/assemble connecting links, and assist in inspection ofanchor jewelry.

3.3.1.2 Offshore Inspection Method

The following list describes personnel and duties for theoffshore inspection methods:

a. The windlass operator runs and stops chain on the order ofthe chief inspector, stopping chain after every 100 feet ofchain movement.

b. The chief inspector coordinates the work among theinspection personnel, gives orders to the windlass operator,rejects or accepts damaged links, and performs visual inspec-tion and measurements.

c. The assistant inspector keeps inspection records, performsvisual inspection, and assists with measurements.d. The MPI inspector performs MPI on anchor jewelry andspare connecting links prior to inspection.e. Roughnecks clean chain, grind out surface defects, changeconnecting links, and assist with inspection of anchor jewelry.

3.3.2 EQUIPMENT

The following equipment is often needed for chain inspec-tion. Its need and availability should be checked before theinspection is started.

a. Workboat (offshore inspection method).b. Dockside crane or other suitable equipment to lay outchain (dockside inspection method).

Figure 4—Offshore Inspection Method

UPPER FAIRLEAD


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c. High-pressure fire hose.d. Sandblasting equipment.e. MPI equipment.f. Go-no-go gauge for chain diameter measurement (Figure2, Part e).g. Go-no-go gauge for maximum allowable length over fivelinks (see “Offshore Inspection Method,” in Figure 5, Part a)or go-no-go gauge for maximum allowable length of individ-ual link (see “Dockside Inspection Method,” Figure 5, Part b).

h. Steel wire brush.i. Hammer.j. Spare connecting links that have been inspected by MPI(a sufficient number of connecting links must be prepared

for replacing existing connecting links and damaged com-mon links).k. Grinder.l. Diameter caliper (Figure 2, Part d).m. Measuring tape.n. Tape recorder.o. Spray paint.p. Camera.q. Lighting equipment.

3.3.3 ARRANGEMENT

3.3.3.1 Dockside Inspection Method

For arrangement in the dockside inspection method, oneshould lay out the chain on a dry area in rows approximately100 feet long. If this arrangement is impractical, one shoulduse spray paint to mark every 100 feet of chain.

3.3.3.2 Offshore Inspection Method

The inspector should stand close to the windlass or theupper fairlead. Chain inspections have been carried out on aspecially built platform near the lower fairlead of a semisub-mersible, but this practice is discouraged because it canendanger the inspectors if the chain breaks at the windlass.For chain systems, inspection could be accomplished on thedeck of a large anchor-handling boat that has adequate han-dling gear and chain lockers.

3.3.4 CLEANING

One should clean the chain with a high-pressure hose. Alsomarine growth and corrosion scale should be removed atevery 100 feet of chain and at places close examination isneeded.

3.3.5 INSPECTION STEPS

3.3.5.1 Visual Inspection

One hundred percent of the chain is visually inspected formissing studs, bent links, corrosion, sharp gouges, loosestuds, cracks, and wear. When using the offshore inspectionmethod, the line speed should be less than 30 feet per minute.When chain abnormalities are suspected, the chain movementshould be stopped for close examination. The inspectorshould also watch the movement of the chain passing throughthe wildcat. Jumping of chain over the wildcat may indicatemisfit between the chain and wildcat.

The inspector should tap each stud with a hammer to checkfor loose studs. An experienced inspector can detect loosestuds by listening to the tone of the tapping.

The offshore inspection method is most effective whereone inspector checks the links in a vertical plane whileanother inspector checks the links in a horizontal plane.

A. OFFSHORE INSPECTION METHOD

B. DOCKSIDE INSPECTION METHOD (OPTION 1)

C. DOCKSIDE INSPECTION METHOD (OPTION 2)

Figure 5—Chain Length Measurement


6 API R

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The last portion of chain should be brought on board thedeck of the drilling vessel or the deck of the workboat forinspection.

3.3.5.2 Connecting-Link Inspection

To perform a connecting-link inspection, the inspectorshould dismantle all connecting links and inspect by MPI orreplace with links that have been examined by MPI.

3.3.5.3 Measurement

3.3.5.3.1

One should measure the following parametersonce at every 100 feet of chain and on both sides of each con-necting link. If chain problems are found, more measure-ments may be needed.

For chain diameters in two perpendicular directions asshown in Figure 2, Part a, one should remove corrosion scaleand marine growth before measuring diameters. The diametermeasurement should be performed at the location with theworst reduction in cross-sectional area, which is normally thegrip area or the area that rubs against the windlass wildcat(see Figure 2, Part b). If the grip area has the worst reduction

and the offshore inspection method is used, two diametersshould be measured as shown in Figure 2, Part c.

In the offshore inspection method, length over five linkscan be measured with a go-no-go gauge (see Figure 5, Part a).For the dockside inspection method, length over five linkscannot be measured accurately since the chain is not undertension. Therefore, the length of individual links should bemeasured by a go-no-go gauge as shown in Figure 5, Part b.Another option of chain length measurement for docksideinspection is shown in Figure 5, Part c.

3.3.5.3.2

If grinding is performed to remove surfacedefects, one should measure link diameter after grinding witha diameter caliper as shown in Figure 2, Part d.

3.3.5.4 Anchor and Anchor Jewelry Inspection

3.3.5.4.1

The inspector should visually inspect all anchorjewelry such as anchor shackles, swivels, open links, and con-necting links. In addition, certain areas as shown in Figure 6should be inspected by MPI. MPI procedures are presented inAppendix A.

Figure 6—Inspection of Anchor Jewelry


I

N

-S

ERVICE

I

NSPECTION

OF

M

OORING

H

ARDWARE

FOR

F

LOATING

D

RILLING

U

NITS

7

MPI should be conducted under the supervision of an oper-ator’s representative or a representative from recognized clas-sification societies. The areas to be examined by MPI shouldbe clearly marked on each item. One should dismantle allconnecting links and other anchor jewelry as required.

Anchors should be visually inspected. Attention should begiven to welds, corners, and areas of high stress.

3.3.5.5 Winching Equipment Inspection

The working conditions of the windlasses, fairleads, chainstoppers and chain chasers, and the like, should be checked.

3.3.5.6 Inspection Record

The following information should be included on theinspection record:

a. Name of the chain manufacturer, size and grade of chain,and method of securing studs (unwelded, one side welded, orboth sides welded). b. Operation history, including the age of the chain, inspec-tion and failure history, and previous operating locations.c. Inspection date and names of inspectors.d. Locations and nature of all chain abnormalities, plus thecorrective measures taken.e. Chain diameter and length over five links (or length of anindividual link) and locations where measurements are taken;also the general conditions of the last section inspected.f. Locations of connecting links.g. MPI results.h. Recommendations for further action to be taken.

3.4 Guidelines for Rejecting Chain Components

Links having any of the following problems should beremoved:

a. A missing stud.b. A noticeable out-of-plane bending (see Figure 7).

c. An average of two measured diameters less than 95 per-cent of the nominal diameter (about a 10 percent reduction ofcross-sectional area) or a diameter in any direction less than90 percent of the nominal diameter.d. A crack at the toe of the stud weld extending into the basematerial.e. Surface cracks or sharp gouges that cannot be eliminatedby light grinding. The link should be rejected if the chaindiameter is reduced to less than 90 percent of the nominaldiameter after grinding.f. Excessively loose stud. Since it is difficult to quantifyexcessive looseness of chain studs, the decision to reject oraccept a link with a loose stud depends on the experience andjudgment of the inspector. As a point of reference, if a studcan move more than

1

⁄

8

inch (3 millimeters) axially or morethan

1

⁄

16

inch (5 millimeters) laterally in any direction (seeFigure 8, Part a), rejection of the link should be considered.Similarly, if a gap of more than

1

⁄

8

inch (3 millimeters) existsbetween the stud end and the link in a link with a stud weldedon one end, rejection of the link should also be considered(see Figure 8, Part b).

g. Cracks detected by MPI in the internal locking area ofconnecting links. External surface defects in connecting linksare not cause for rejection if they can be eliminated by grind-ing to a depth of no more than 8 percent of the nominal diam-eter of the chain.h. Length over five links exceeding 23.25 times the nominalchain diameter (offshore inspection method) or the length ofan individual link exceeding 6.15 times the nominal chain

Figure 7—Discard Criterion for Bent Links

A. LOOSE STUD

B. LARGE GAP BETWEEN STUD AND LINK

Figure 8—Examples of Severely Loose Studs


8 API R

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diameter (dockside inspection method). The upper limit val-ues of length over five links and length of the individual linkfor different sizes of used chain can be found in Table 1.i. Excessive wear or a deep surface crack on anchor shack-les, open links, or swivels. Moderate wear and surface cracksthat can be eliminated by light grinding are acceptable for theanchor jewelry. They should be rejected, however, undereither of the following conditions:

1. Reduction in cross-section area due to wear and grind-ing is more than l0 percent. This is equivalent to a 5 per-cent reduction in the average diameter for distributed wearor grinding. 2. Reduction in diameter or critical thickness in anydirection is more than l0 percent.

3.5 Guidelines for Chain Repair, Removal, and Replacement

3.5.1

Individual links that meet the discard criteria shouldbe removed and replaced with connecting links that havebeen examined by MPI.

3.5.2

If a substantial number of links in a chain sectionmeet the discard criteria, the chain section should beremoved, and the chain can be joined again by connectinglinks that have been examined by MPI.

3.5.3

The number of connecting links in a mooring lineshould not exceed an average of one per 400 feet outboardline length. Furthermore, the total number of connecting linksin a mooring line should be no more than ten, excluding theconnecting links at the anchor end.

3.5.4

If a large number of links meets the discard criteriaand these links are distributed in the whole length, the chainshould be replaced with a new chain.

3.5.5

Rewelding of loose studs in the field is undesirablefor the following reasons:

3.5.5.1

Welding in the field may produce hard heat-affected zones that are susceptible to cold cracking.

3.5.5.2

Hydrogen embrittlement may occur from absorp-tion of moisture from the atmosphere or welding electrodes.

Weld repairs on loose studs should be delayed as long aspossible. Where a few links are found with loose studs in ashort section of a chain, it is recommended that this portion ofthe chain be cut out and a connecting link put in.

If the major portion of the chain has loose studs, the chainshould be scrapped. In the case where the chain is not too old,but contains many loose studs, the chain may be recondi-tioned onshore at a qualified chain manufacturer where theloose studs are rewelded at one end and the chain is heat-treated again. However, this practice cannot be applied toGrade 4 chains, for which stud welding is normally prohibited.

Studs in chain links serve two purposes: (a) to avoid knotsor twist problems during handling operations and (b) to sup-port the links and prevent the sides of the links from deflect-ing inward during tensile loading, thus preventing highbending stresses in the chain.

It is important to keep the stud in place to accomplish thepurposes just discussed. Although weld repair of loose studsshould be discouraged, excessive stud movement can be pre-vented by careful welding using the proper electrode, preheat,interpass temperature, and rate of cooling after welding.Some regulatory bodies permit field rewelding of studs in oilrig quality chains. However, they normally require the weld-ing contractor to submit welding specifications for theirapproval prior to such weld repair.

3.5.6 Any grinding to eliminate shallow surface defectsshould be done parallel to the longitudinal direction of thechain, and the groove should be well rounded and form asmooth transition to the surface. The ground surface shouldbe examined by MPI.

3.5.7 It is recommended that replacements for faultymooring jewelry such as connecting links, anchor shackles,

Table 1—Upper Limit of Length Over Five Links And Length of Individual Link for Used Chain

Nominal Diameter (inches)

Length Over 5 Links (23.25D, inches)

Length of Individual Link (6.15D, inches)

2 46.5 12.321⁄8 49.4 13.121⁄4 52.3 13.823⁄8 55.2 14.621⁄2 58.2 15.425⁄8 61.0 16.123⁄4 64.0 16.927⁄8 66.8 17.73 69.8 18.531⁄8 72.7 19.231⁄4 75.5 20.033⁄8 78.5 20.831⁄2 81.4 21.535⁄8 84.3 22.333⁄4 87.2 23.137⁄8 90.1 23.84 93.0 24.641⁄8 95.9 25.441⁄4 98.8 26.143⁄8 101.7 26.941⁄2 104.7 27.745⁄8 107.4 28.443⁄4 110.5 29.247⁄8 113.3 30.05 116.3 30.851⁄8 119.2 31.551⁄4 122.0 32.353⁄4 125.0 33.151⁄2 127.8 33.855⁄8 130.8 34.653⁄4 133.7 35.457⁄8 136.6 36.1


IN-SERVICE INSPECTION OF MOORING HARDWARE FOR FLOATING DRILLING UNITS 9

swivels, wire rope sockets, and pelican hooks be made offorged material.

3.6 Recommended Inspection ScheduleA chain inspection schedule should be based on the age

and condition of the chain and areas of operation. However,the inspection intervals should not exceed those specified inTable 2.

In addition to the major inspections, chain should bechecked for visible defects frequently during anchor retrieval.

4 GUIDELINES FOR IN-SERVICE INSPECTION OF MOORING-WIRE ROPE AND ANCHOR HANDLING EQUIPMENT

4.1 Common Problems with Used Mooring-Wire Rope

Mooring-wire ropes receive rough treatment in service,which may result in various types of damage. Inspectorsshould be particularly attentive to the common wire ropeproblems described in the following paragraphs.

4.1.1 BROKEN WIRES

4.1.1.1 Broken Wires at the Termination

Broken wires at the termination, even if few in number,indicate high stresses at the termination and may be causedby incorrect fitting of the termination, fatigue, overloading, ormishandling during deployment or retrieval.

4.1.1.2 Distributed Broken Wires

The nature of the wire breaks is an important key to diag-nosing wire rope problems. For example, a crown break onthe top of the strand may indicate excessive tension, fatigue,wear, or corrosion. Necking down at the broken end of thewire indicates failure in tension. Broken faces perpendicularto the axis of the wire indicate fatigue. Reduced cross sec-tions of the wire breaks may indicate corrosion and wear. Anexample of distributed crown breaks is given in Figure 9, andtypical wire fractures are shown in Figure 10.

Valley breaks at the interface between two strands indicatetightening of strands. This is normally caused by internal cor-rosion reducing the area of the core or by a broken core. Val-

ley breaks can also be caused by tight sheaves, extremelysmall sheave-to-rope diameter ratios, and high loads.

4.1.1.3 Locally Grouped Broken Wires

If broken wires are closely grouped in a single strand oradjacent strands, as shown in Figure 11, there may have beenlocal damage at this point. When wire breakage of this typebegins, it will usually worsen. Such concentrated wire break-age will upset the balance of loads carried by the strands.

4.1.2 CHANGE IN ROPE DIAMETER

The rope diameter can be reduced by external wear, inter-wire and interstrand wear, stretching of the rope, and corro-sion. Excessive reduction in diameter can substantially reducethe strength of the rope. Therefore, the diameter should bemeasured and recorded periodically throughout the life of therope. The new rope diameter should also be measured andrecorded.

An increase in the rate of change in diameter may indicateaccelerated corrosion or stretching of the rope due to over-load. A localized decrease in diameter at any point in the ropeas shown in Figure 12 may indicate a break in the core. Anyincrease in wire rope diameter is also a cause for concern,since it may indicate swelling of the core due to internalcorrosion.

4.1.3 WEAR

Wear of the crown wires of outer strands in the rope can becaused by rubbing against the fairlead sheaves or hard seaf-loor. In particular, external wear of mooring-wire rope can becaused by dragging the wire rope on hard seafloor duringanchor deployment or retrieval.

Internal wear is caused by friction between individualstrands and between wires in the rope, particularly when it issubject to bending. Internal wear is usually promoted by lackof lubrication.

Wear reduces the strength of wire ropes by reducing thecross-sectional area of the steel. Progression of external wearis illustrated in Figure 13.

4.1.4 CORROSION

Corrosion in marine atmosphere not only decreases thebreaking strength by reducing the metallic area of the rope,

Table 2—Chain Inspection Intervals

Number of Years in ServiceMaximum Intervals

Between Major Inspections0–3 36 months4–10 24 months

over 10 8 months~

Source: Reprinted with permission of American Iron and Steel Institute,from Wire Rope User’s Manual, © 1981 American Iron and Steel Institute.

Figure 9—Examples of Distributed Crown Wire Breaks


10 API RECOMMENDED PRACTICE 2I

but also accelerates fatigue by causing an irregular surfacethat will invite stress cracking. Severe corrosion may reducea rope’s elasticity.

Corrosion of the outer wires as shown in Figure 14 may bedetected visually. Progression of external corrosion is illus-trated in Figure 15. Internal corrosion is more difficult todetect than external corrosion that frequently accompanies it,but the following indications may be recognized:

4.1.4.1 In positions where the rope bends around fairleadsheaves, a reduction in diameter usually occurs. However, instationary ropes, an increase in diameter could occur due to

the buildup of rust under the outer layer of strands, althoughthis condition is rare for mooring-wire ropes.

4.1.4.2 Loss of gap between strands in the outer layer ofthe rope, frequently combines with valley wire breaks andloss of flexibility.

4.1.5 LOSS OF LUBRICATION

Proper and thorough lubrication is important to permit thewires and strands to work without excessive internal wear andto inhibit corrosion. Operating a wire rope in frequent bend-ing service without lubrication will reduce its life to only a

A. FAILURE DUE TO TENSILE OVERLOADING CHARACTERIZED BY THE CUP CONE CONFIGURATION

Fatigue failure—initial fracture from fatigue and final fracture by shear.

Fatigue failure—straight across.

Fatigue failure—Z-shaped.

B. FATIGUE FAILURES CHARACTERIZED BY NO REDUCTION IN CROSS SECTION AREA

Figure 10—Typical Wire Fractures



fraction of normal life because of internal wear. Figure 16shows a large reduction of cross-sectional area due to internalwear in the wires of a wire rope that has lost internal lubrica-tion. A nongalvanized mooring-wire rope working in amarine environment without lubrication can rapidly developsevere corrosion and fail in corrosion fatigue in a few months.

Loss of internal lubrication is normally caused by a wash-ing out of lubricant during service. A great variety of lubri-cants are used in wire rope manufacturing, and some of thelubricants can be easily leached out by wave actions. Figure17, Part a shows heavy internal corrosion in a mooring-wirerope caused by lack of internal lubrication. When animproper lubricant applied to the wire rope during manufac-turing was rapidly lost in service, severe corrosion developed,leading to a mooring-line failure. On the other hand, as shownin Figure 17, Part c, a dismantled strand with lubrication onthe internal wires shows no evidence of internal corrosion.Figure 17, Part b shows a dry rope with no internal lubrica-tion. In this case, internal wear and corrosion are not obvious,but may soon develop.

External lubrication is difficult to maintain for mooringwire ropes. Some drilling contractors have a policy to relubri-cate wire ropes periodically. However, relubrication has notbeen proven to be effective in preventing internal corrosion,which is the main cause of many mooring-wire rope failures.In addition, relubrication may violate pollution control codesin many areas.

Figure 11—Locally Grouped Broken Wires

Source: Reprinted with permission of International Organization for Stan-dardization from “International Standard ISO 4309:1993,” © 1993 Interna-tional Organization for Standardization.

Figure 12—Local Decrease in Rope Diameter

SLIGHT FLATS ON OUTER WIRES. LITTLE REDUCTION IN ROPE DIAMETER

INCREASED LENGTH OF FLATS ON INDIVIDUAL OUTER WIRES

FLATS ON INDIVIDUAL WIRES LONGER, AFFECTING ALL CROWN WIRES IN EACH STRAND. MARKED REDUCTION IN ROPE SIZE

FLATS ON INDIVIDUAL WIRES NOW ALMOST CONTINUOUS—STRANDS APPEAR SLIGHTLY FLATTENED AND WIRES ARE NOTICEABLY THIN

FLATS TOUCH EACH OTHER, WIRES BECOMING SLACK WITH AN ESTIMATED REDUCTION IN SIZE OF 40%


Figure 13—Progression of Wear in Wire Rope



4.1.6 DEFORMATION

Distortion of the rope from its normal construction istermed deformation and may result in an uneven stress distri-bution in the rope. Kinking, bending, scrubbing, crushing,and flattening are common wire rope deformations.

A kink is a deformation in the rope created by a loop thathas been tightened without allowing for rotation about itsaxis. Unbalance of rope construction due to kinking willmake a certain area of the rope disproportionately susceptibleto excessive wear (see Figure 18, Part a). Bends are angulardeformations of the rope caused by external influence (seeFigure 18, Part b).

Scrubbing and crushing of wire rope as shown in Figure l9,Parts a, b, and c can be caused by improperly winding therope on the winch drum. Flattening of wire rope (see Figure19, Part d) may occur if the rope escapes from the winchdrum and is pinched between the drum and another member.These problems are normally caused by a malfunction of the

RUST IN GUSSET AND LARGE GAP BETWEEN WIRES

Figure 14—Wire Rope with Heavy External Corrosion

FLAT SURFACE DUE TO WEAR

LARGE CROSS SECTIONOF INTERNAL WIRESINDICATES ABSENCE OFINTERNAL CORROSION

LARGE GAP

SMALL CROSS SECTIONOF WIRE DUE TOCORROSION

A. BEGINNING OF SURFACE OXIDATION

B. WIRES ROUGH TO TOUCH. GENERAL SURFACE OXIDATION

C. OXIDATION NOW MORE MARKED

D. SURFACE WIRE NOW GREATLY AFFECTED BY OXIDATION. PITTING OBVIOUS. RUST IN GUSSETS

E. SURFACE HEAVILY PITTED AND WIRE QUITE SLACK


Figure 15—Progression of External Corrosion



level wind or failure to maintain proper line tension whilewinching.

Wire ropes with only slight deformations would lose nosignificant strength. Severe distortions, however, can acceler-ate wire rope deterioration and lead to premature rope failure.

4.1.7 THERMAL DAMAGE

Serious heat damage to a mooring wire rope is rare in nor-mal service. Nevertheless, prompt attention should be givento any indication that excessively high or low temperature hascaused damage to the rope.

Minor variations in temperature may affect the lubricant.When heated, some lubricants become thin and drip off; andwhen cooled, some oils and greases stiffen and lose lubricity.

Sustained usage at temperatures in excess of 400°F maycause metallurgical changes in a wire rope, with accompanyingtensile and fatigue strength reductions. Such temperatures canoccur in electrical arcing or exposure to fire, flame, or hotgases. Discoloration of the metal can indicate thermal damage.

The effect of temperatures below 0°F on wire rope isunclear except for their known detrimental effect on lubri-cants. No published data on wire rope performance at lowtemperatures and under normal loads is known.

4.2 Recommended Inspection Method

4.2.1 GENERAL

In-service wire rope for mobile offshore drilling units isusually inspected with the assistance of a workboat as shown

in Figure 20. Two common methods for wire rope inspectionare described below.

4.2.2 INSPECTION DURING ANCHOR RETRIEVAL

The wire rope is inspected in conjunction with anchorretrieval. Such inspection requires no additional equip-ment since a workboat is always available during anchorretrieval. However, the inspection can substantially slowdown the anchor retrieval operation and delay a rig moveschedule.

Figure 16—Wear of Internal Wires Caused by Lackof Lubricant Between Wires

A. HEAVY CORROSION CAUSED BY LACK OF INTERNAL LUBRICATION

B. DRY ROPE WITH NO INTERNAL LUBRICATION. INTERNAL WEAR AND CORROSION ARE NOT OBVIOUS BUT MAY SOON DEVELOP

C. ROPE WITH PROPER INTERNAL LUBRICATION. NO INTERNAL WEAR AND CORROSION EXPECTED

Figure 17—Effect of Internal Lubrication on Wire Rope



4.2.3 DOCKSIDE INSPECTION

The drilling vessel stays in a dock or harbor for repair, spe-cial survey, and the like, and a workboat is contracted for thewire rope inspection. This method has two disadvantages.First, the inspection is economical only when it coincideswith rig repair or special survey. Second, because the rig’slocation is close to land, the radius for workboat operationcan be limited on one side of the rig. To inspect all mooringlines, rotating the rig 180 degrees would be necessary in somecases, and this would delay the inspection and increase oper-ating costs. Therefore, inspection during anchor retrieval ispreferred.

4.3 Recommended Inspection Procedure

4.3.1 PERSONNEL

The recommended inspection procedure includes the fol-lowing personnel and their duties:

a. The winch operator runs and stops the winch on the orderof the chief inspector. b. The chief inspector coordinates the work among inspec-tion personnel, gives orders to the winch operator, performsvisual inspections and measurements, and rejects or acceptswire rope. c. The assistant inspector keeps inspection records, performsvisual inspections, and assists with measurements.d. Roughnecks assist with inspections.

4.3.2 EQUIPMENT

The following equipment is often needed in wire ropeinspection; its need and availability should be checked beforethe inspection is started.

a. Workboat.b. Rope calipers (see Figure 21, Part b).c. High-pressure hose.d. Cutting torch.e. Wire rope sockets and filler.f. Lighting equipment.g. Parallel-jaw pliers.h. Camera.i. Tape recorder.j. Measuring tape.k. Sheave gauge.

4.3.3 LENGTH OF ROPE COVERED BY INSPECTION

Although it is desirable to inspect the whole mooring line,it may be impractical in many cases because of operationalconstraints. As a general rule, inspection should cover at leastthe maximum outboard line length that could be deployed.

A. WEAR AND DEFORMATION CREATED AT A PREVIOUSLY KINKED PORTION OF ROPE

B. EXAMPLE OF SEVERE BEND


Figure 18—Kink and Bend of Wire Rope

A. SCRUBBING AT CROSS-OVER OR FLANGE TURNBACK, LARGE NUMBER OF BROKEN WIRES

B. LAYER TO LAYER CRUSHING RESULTING IN BROKEN WIRES

C. LAYER TO LAYER CRUSHING

D. FLATTENED PORTION DUE TO LOCAL CRUSHING, CREATING UNBALANCE IN THE STRANDS AND ASSOCIATED WITH BROKEN WIRES

Source: A, B, and C Reprinted with permission of International Organiza-tion for Standardization from “International Standard ISO 4309:1993,” ©1993 International Organization for Standardization.

Source: D Reprinted with permission of American Iron and Steel Institute,from Wire Rope User’s Manual, © 1981 American Iron and Steel Institute.

Figure 19—Deformation Caused by Improper Drum Winding



The inspector should determine the length of rope covered byinspection based on rope deployment history and future oper-ations plan.

4.3.4 ARRANGEMENT

Wire rope inspection is carried out with the assistance of aworkboat as shown in Figure 20. The workboat first picks upthe anchor and then moves away from the drilling vessel. Atthe same time, the drilling vessel pays out the mooring lineuntil the predetermined outboard line length is reached. Thenthe workboat moves back slowly toward the drilling vesselwhile the winch on the vessel takes in the mooring line of nomore than 30 feet per minute. For more thorough inspection,lower speed of 15 feet to 20 feet per minute is recommended.

The inspectors should stand close to the winch or whereverlighting is adequate and communication with the winch oper-ator is convenient.

4.3.5 CLEANING

The portion of rope covered by mud should be cleanedwith a high-pressure fire hose. Marine growth should beremoved where measurements and close examinations are tobe performed.

4.3.6 INSPECTION STEPS

4.3.6.1 Visual Inspection

While the line is slowly taken in, the inspectors shouldlook carefully for signs of abnormalities such as brokenwires, excessive wear, corrosion, or physical deformations.

They shall examine closely any observed abnormality in thewire rope, with the line movement stopped. The inspectorshould record the nature of each observed abnormality andmake appropriate measurements and estimates to quantify thedamage.

The termination should be closely examined, and the seiz-ing at the termination should be removed to facilitate thedetection of broken wires. Particular attention should also begiven to the portion of rope against fairlead, previous problemareas, and areas in the splash zone.

4.3.6.2 Measurement

The inspector should measure the distance of three laylengths and wire rope diameters in three directions as shownin Figure 21 at the beginning, middle, and the end of the por-tion of the rope being inspected. If substantial diameterreduction or rope stretching is found, further measurementsshould be taken along the line. In addition to these measure-ments, the general condition of the rope, such as degree ofwear and corrosion at the three places, should also be recorded.

4.3.6.3 Internal Inspection

4.3.6.3.1 Selection of rope for internal inspection shouldbe made as follows: If all the wire ropes onboard the vesselare made by one manufacturer, at least one mooring lineshould be inspected for internal corrosion. Internal inspectionshould first be performed on the oldest rope or the rope withthe most severe external corrosion if the ages of the ropes arenot known. If internal corrosion is detected in the first rope

Figure 20—Wire Rope Inspection with the Assistance of a Workboat



internally inspected, internal inspection should be performedon the rest of the ropes.

If the ropes are made by more than one manufacturer, thepreceding practice should be followed for the ropes made byeach manufacturer.

4.3.6.3.2 The internal inspection procedure is as follows:

a. Cut a length of approximately 15 feet to 20 feet of ropeat the end. Remove a 2-foot to 3-foot section from the cutend and dismantle it for inspection of internal wires (seeFigure 22).

b. If internal corrosion is observed, repeat step a. until a goodinternal condition is found. The lengths of rope to be removedin subsequent cuttings should be determined by theinspectors.c. If no internal corrosion is found, reterminate the rope witha socket and put it in service again. An example of acceptableinternal conditions is illustrated in Figure 17, Part c. It may beadvisable to remove a rope section of 20 feet from the cut end(see Figure 22). A break test performed for this rope sectionmay provide useful information on the remaining strength ofthe rope.

A. DEFINITION OF LAY LENGTH

B. DIAMETER MEASUREMENT

Source: Reprinted with permission of International Organization for Standardization from “InternationalStandard ISO 4309:1993,” © 1993 International Organization for Standardization.

Figure 21—Lay Length and Diameter Measurement



4.3.6.4 Inspecting the Last Portion of Rope

Inspecting the last approximately 200 feet of wire rope isdifficult for an all-wire-rope system. However, if the loca-tion of the wire rope can be reached by crane, and deckspace on the vessel is available, the anchor and the last por-tion of the wire rope can be picked up and laid on deck bythe crane for inspection. Otherwise, the anchor and the lastportion of wire rope can be brought on board the workboatand inspected there.

4.3.6.5 Inspecting Anchor Jewelry and Miscellaneous Items

All anchor jewelry such as anchor shackles, swivels, openlinks, and connecting links should be inspected in the mannerspecified in Section 3.

Sockets for reterminating wire rope should be visuallyinspected. In addition, the eyes of the sockets should beexamined by MPI. Open links, connecting links, and shacklesused to connect wire rope, and chain should be inspected bythe same method for anchor jewelry inspection (see Figure 6).

4.3.6.6 Inspection Record

The following should be recorded on the inspection record:

a. The manufacturer, size, construction, grade of steel, coat-ing (galvanized or not), and age of the wire ropes.b. The operation history, including inspection and failure his-tory and previous operating locations.c. The inspection date and names of inspectors.d. Locations and nature of all wire rope abnormalities, andcorrective measures taken.e. Wire rope diameter and lay length measurements, andgeneral conditions where the measurements are taken.f. Recommendations for further action to be taken.

4.4 Guidelines for Rejecting Wire Rope

4.4.1 GENERAL

A wire rope should be rejected when any of the followingconditions is found. In each case, the rope should be replacedor the damaged portion removed as prescribed.

4.4.2 DISTRIBUTED CROWN BROKEN WIRES

The number of visible broken wires distributed within a laylength reaches or exceeds the limits presented in Table 3.These limits are equivalent to about an 8 percent reduction incross-sectional area of the rope or a 10 percent reduction instrength when unbalance of load is taken into consideration.Rope constructions listed in Table 3 are commonly used inmooring wire ropes and are illustrated in Figure 23. (A laylength is the distance parallel to the axis of the rope in which astrand makes one complete helical convolution about the core.For a six-strand regular lay rope, a lay length is about 6 times to7 times the nominal diameter, as shown in Figure 21, Part a).

Figure 22—Internal Inspection of Wire Rope

Table 3—Criteria for Crown Broken Wires

Rope Construction

Number of Outer Wires in a Strand

Number of Distributed

Broken Wires in One Lay

Length

Number of Adjacent

Broken Wiresin One Strand

Number of Broken Wires

at Termination

6 x 26 10 8 3 36 x 25 or 6 x 31 12 10 4 46 x 36 14 13 5 56 x 41 or 6 x 49 16 17 6 66 x 46 18 21 8 8Equivalent reduction incross-sectional areaa 8% 3% 3%

aThis information can be used to calculate the allowable number of broken wires for rope constructions not listed in this table.



4.4.3 GROUPED BROWN BROKEN WIRES

In this group, the number of adjacent broken wires in onestrand reaches or exceeds the limits presented in Table 3.These limits are equivalent to about a 3 percent reduction inthe cross-sectional area of the rope or a 17 percent reductionin the cross-sectional area of the strand. This criterion appliesto damages concentrated in a small area of a strand as shownin Figure 11.

4.4.4 VALLEY BROKEN WIRES

In this group, two adjacent wires are broken in the valley. Avalley break is initiated at the interface between two strands.One should discern a valley break from a wire break that isinitiated at the crown of a strand first, and broken off at thevalley later.

4.4.5 BROKEN WIRES AT TERMINATION

In this group, the number of broken wires within 12 inchesof the termination reaches or exceeds the limits presented inTable 3. These limits are equivalent to about a 3 percentreduction in cross-sectional area of the rope.

Rope replacement is normally not required for this condi-tion, but a minimum of 15 feet of rope at the end should beremoved and the rope reterminated. Both spelter (zinc)poured and resin sockets are acceptable. Recommended pro-

cedures for retermination of wire rope can be found inAppendix B.

4.4.6 WEAR AND STRETCH

In this group, the average of the three measured diametersis less than 94 percent of the nominal diameter.

4.4.7 INTERNAL CORROSION AND WEAR

In this group, internal corrosion and wear are observed.The wire rope shown in Figure 17, Part a is an example ofextreme internal corrosion. However, a clear indication ofinternal corrosion and wear combined with a lack of lubrica-tion is a justification for discard.

Where internal corrosion and wear are not obvious butinternal lubrication is absent, as shown in Figure 17, Part b,the rope is acceptable for use temporarily; however, internalinspection should be repeated within six months.

4.4.8 DEFORMATIONS

Deformations include any of the conditions listed below:

a. Kinking.b. Severe bending.c. Severe scrubbing.d. Severe crushing.e. Severe flattening.

Figure 23—Common Rope Constructions for Mooring Applications



Since it is difficult to quantify wire rope deformations, thedecision to accept or reject a deformed rope must depend onthe experience and judgment of the inspector. As a point ofreference, Figures 18 and 19 illustrate acceptable and unac-ceptable wire rope deformations.

4.4.9 CORE DETERIORATION

In this group, there is an abrupt reduction in the diameter(see Figure 12), which is usually accompanied by an increasein lay length.

4.4.10 SUMMARY

Each of the preceding guidelines deals with one type ofwire rope damage, but sometimes several types of damagemay occur in one area of a wire rope. Even though none ofthe guidelines is violated, the rope should be rejected whenthe combined effect of the damage jeopardizes the integrity ofthe rope. Consider a case, for example, where the number ofdistributed broken wires in one area of a rope is less than, butclose to, the limit specified in Table 3, and in addition thisarea has considerable external corrosion and wear. In thiscase, the rope should be replaced as soon as possible.

4.5 Recommended Inspection ScheduleInspection should be scheduled according to the conditions

of the rope detected during the prior inspection. If the condi-tion of the rope is close to a rejection criterion, more frequentinspections should be made. However, the inspection inter-vals should not exceed those specified in Table 4.

4.6 Recommendations for Proper Use and Maintenance of Mooring-Wire Rope

Recommendations for proper use and maintenance ofmooring-wire rope are as follows:

a. Reterminate mooring-wire rope on mobile offshore drill-ing units every 18 months. A minimum of 15 feet of ropeshould be cut and the rope reterminated.

b. When deploying wire rope on hard seafloor, maintainproper tension in the rope by applying the dynamic brake toavoid dragging the wire rope on the seafloor.c. Maintain a tension when winching in the mooring lines. d. Avoid, if possible, test loading anchors when the wirerope is at the riser point where a new layer starts on thewinch drum.e. Gauge the fairlead sheave grooves at convenient times,such as during special survey or rig repair. If the groove issubstantially under gauge, replace or repair the fairleadsheave. The radius of the fairlead sheave groove should not beless than the minimum radius for worn groove specified inTable 5. Fairlead sheaves should also be carefully evaluated foroversize grooves which can also cause damage to the wire rope.f. Check the level wind of the winch periodically to ensureits proper function.

4.7 Inspection of Anchor-handling Equipment and Termination of Pendant Wire Rope

4.7.1 INSPECTION

The anchor-handling equipment on the workboat should beinspected to ensure a safe operation. The discard criteria formooring-wire rope would equally apply to wire ropes forpendant lines and work lines on a workboat. However, theinspection method, procedure, and schedule for pendant wirerope could be substantially different and should be deter-mined by the operating personnel based on their experience,the pendant system, and the equipment on the workboat.

Miscellaneous connecting hardware, such as sockets,shackles, and connecting links for pendant lines and worklines, should be inspected in the same manner described inprevious sections. Pelican hooks and similar devices for tempo-rarily securing a pendant line should be examined by MPI.

4.7.2 TERMINATION

Three types of wire rope termination are acceptable forpendant lines: spelter-poured or resin socket, swaggedsocket, and thimbled mechanical splice, as shown in Figure24. The swagged sockets and thimbled mechanical splicesshould be made at the manufacturers’ facilities. Only thespelter-poured and resin sockets can be made in the field.

Recommended procedures for making spelter- (zinc-)poured socket and thermo-set resin socket can be found inAppendix B.

Table 4—Rope Inspection Intervals

Number of Years in ServiceMaximum Intervals

Between Major Inspections0–2 18 months3–5 12 months

over 5 9 months



Table 5—Minimum Sheave-Grooveand Drum-Groove Dimensions

Groove Radius Nominal Rope Diameter New Worn

inches mm inches mm inches mm1⁄4 6.4 0.135 3.43 0.129 3.285⁄16 8.0 0.167 4.24 0.160 4.063⁄8 9.5 0.201 5.11 0.190 4.837⁄16 11 0.234 5.94 0.220 5.591⁄2 13 0.271 6.88 0.256 6.509⁄16 14.5 0.303 7.70 0.288 7.325⁄8 16 0.334 8.48 0.320 8.133⁄4 19 0.401 10.19 0.380 9.567⁄8 22 0.468 11.89 0.440 11.181 26 0.543 13.79 0.513 13.0311⁄8 29 0.605 15.37 0.577 14.6611⁄4 32 0.669 16.99 0.639 16.2313⁄8 35 0.736 18.69 0.699 17.7511⁄2 38 0.803 20.40 0.759 19.2815⁄8 42 0.876 22.25 0.833 21.1613⁄4 45 0.939 23.85 0.897 22.7817⁄8 48 1.003 25.48 0.959 24.362 52 1.085 27.56 1.025 26.0421⁄8 54 1.137 28.88 1.079 27.4121⁄4 58 1.210 30.73 1.153 29.2923⁄8 60 1.271 32.28 1.199 30.4521⁄2 64 1.338 33.99 1.279 32.4925⁄8 67 1.404 35.66 1.339 34.0123⁄4 71 1.481 37.62 1.409 35.7927⁄8 74 1.544 39.22 1.473 37.413 77 1.607 40.82 1.538 39.0731⁄8 80 1.664 42.27 1.598 40.5931⁄4 83 1.731 43.97 1.658 42.1133⁄8 87 1.807 45.90 1.730 43.9431⁄2 90 1.869 47.47 1.794 45.5733⁄4 96 1.997 50.72 1.918 48.724 103 2.139 54.33 2.050 52.0741⁄4 109 2.264 57.51 2.178 55.3241⁄2 115 2.396 60.86 2.298 58.3743⁄4 122 2.534 64.36 2.434 61.825 128 2.663 67.64 2.557 64.9551⁄4 135 2.804 71.22 2.691 68.3551⁄2 141 2.929 74.40 2.817 71.5553⁄4 148 3.074 78.08 2.947 74.856 154 3.198 81.23 3.075 78.11

Note: Values given are applicable to grooves in sheaves and drums; they arenot generally suitable for pitch design since this may involve other factors.Further, the dimensions do not apply to traction-type elevators; in this cir-cumstance, drum- and sheave-groove tolerances should conform to the eleva-tor manufacturer’s specifications. Modern drum design embraces extensiveconsiderations beyond the scope of this publication. It should also be notedthat drum grooves are now produced with a number of oversize dimensionsand pitches applicable to certain service requirements.

A. SPELTER POURED OR RESIN SOCKET (MANUFACTURED OR FIELD MADE)

B. SWAGGED SOCKET (MANUFACTURED ONLY)

C. THIMBLED MECHANICAL SPLICE (MANUFACTURED ONLY)

Source: Reprinted with permission of American Iron and Steel Institute,from Wire Rope User’s Manual, © 1981 American Iron and Steel Institute.

Figure 24—Acceptable Terminationsfor Pendant Wire Rope

A B C


21

APPENDIX A—RECOMMENDED PROCEDURES FORMAGNETIC PARTICLE INSPECTION (MPI)

The following procedures are recommended for MPI:

a. Use qualified MPI inspectors such as those qualified toASNT Level II or equivalent.b. Sandblast surfaces to receive MPI inspection if practical.For areas where sandblasting is not feasible, degreasers, highpressure water equipment, and hand and power wire brushescan be used for surface preparation.c. Use electromagnetic yokes to achieve magnetization ifpractical. The use of prods is not advised. Continuous, ratherthan residual, magnetization is recommended during inspec-tion. Other techniques can be applied by agreement.d. Use unrectified single-phase AC current. If this current isnot available, other types of current can be used.

e. Demonstrate proper magnetization and areas of coveragein calibration tests using test specimens containing cracks or amagnetic field strength indicator.f. Use a contrast coating before inspection to enhance indi-cations. Suggested color combinations include yellow coatingfor black particles, and white or yellow coating for red parti-cles. The coating should cover the area to be inspected, butnot the area of contact with the yoke.g. Use wet magnetic particles from mist-driven applicators orsqueeze bottles. Identify all indications directly on the steelsurface for subsequent evaluation. Carry out grinding orrepair only by agreement.h. Demagnetization is normally not necessary. It is per-formed only under special circumstances.i. Refer to ASTM E709 or equivalent specifications for MPIprocedural details not covered herein.


23

APPENDIX B—SOCKETING

B.1 Zinc-poured SocketingThe following steps should be carefully adhered to in the

order given.

a. Measure the rope ends to be socketed. The rope endshould be of sufficient length so that the ends of the unlaidwires (from the strands) will be at the top of the socket bas-ket. (see Figure B-1, View l).b. Apply serving at base of socket. Apply a tight wire servingband at the point where the socket base will be, for a length oftwo rope diameters. (see Figure B-1, Views 2 and 3).c. Broom-out strand wires. Unlay and straighten the individ-ual rope strands and spread them evenly so that they form anincluded angle of approximately 60 degrees. Unlay the wiresof each individual strand for the full length of the rope end—being careful not to disturb or change the lay of the wires andstrands under the serving band. Unlay the wires of an inde-pendent wire rope core in the same manner. A fiber coreshould be cut out and removed as close to the serving band aspossible (see Figure B-1, View 3).d. Clean the broomed-out ends. A suggested cleaning solventfor this step is SC-5 methyl chloroform. It is also knownunder the names Chlorothane VG and 1-1-1 Trichlorethane.

CAUTION: Breathing the vapor of this solvent is harmful; itshould only be used in a well-ventilated area. Be sure to fol-low the solvent manufacturer’s instructions, and carefullyobserve all instructions printed on the label.

Swish the broomed-out rope end in the solvent, then brushvigorously to remove all grease and dirt—making certain thatthe wires are clean to the very bottom close to the servingband (Figure B-1, View 4). Additionally, a solution of muri-atic acid may also be used. If, however, acid is used, thebroomed-out ends should be rinsed in a solution of bicarbon-ate of soda so as to neutralize any acid that may remain on therope. Care should be exercised to prevent acid from enteringthe core; this is particularly important if the rope has a fibercore. Where it is feasible, the best and preferred cleaningmethod for rope ends prior to socketing is ultrasonic cleaning.After this cleaning step, place the broomed-out end upright ina vise, allowing it to remain until all solvent has evaporatedand the wires are dry.

Solvent should never be permitted to remain on the rope oron the serving band since it will run down the wires when therope is removed from the vise.e. Dip the broomed-out rope ends in flux. Prepare a hotsolution of zinc-ammonium chloride flux comparable toZaclon K. Use a concentration of 1 pound of zinc-ammo-nium chloride to 1 gallon of water; maintain this at a tem-perature of 180°F to 200°F. Swish the broomed-out end inthe flux solution, then place the rope end upright in the vise

until such time as the wires have dried thoroughly (see Fig-ure B-1, View 5).f. Close rope ends and place socket. Use clean wire to com-press the broomed-out rope end into a tight bundle that willpermit the socket to be slipped on easily over the wires (seeFigure B-1, View 6). Before placing the socket on the rope,make certain that the socket itself is clean and heated. Thisheating is necessary in order to dispel any residual moisture,and to prevent the zinc from cooling prematurely.

CAUTION: Never heat a socket after it is placed on the rope.To do so may cause heat damage to the rope.

After the socket is on the rope end, the wires should be dis-tributed evenly in the socket basket so that zinc can surroundeach wire. Use extreme care in aligning the socket with therope’s centerline and in making certain that there is a mini-mum vertical length of rope extending from the socket, that isequal to about 30 rope diameters (see Figure B-1, View 7).

Seal the socket base with fire clay or putty, but make cer-tain that this material does not penetrate into the socket base.Should this occur, it would prevent the zinc from penetratingthe full length of the socket basket thereby creating a voidthat would collect moisture after the socket is placed inservice.g. Pour the zinc. The zinc used should meet ASTM Specifi-cation designation B6 Grade (1) High Grade, and FederalSpecification QQ-Z-351-a Amendment I, Interim Amend-ment 2. Pour the zinc at a temperature of 950°F to 970°F (seeFigure B-1, View 8); make allowances for cooling if the zincpot is more than 25 feet from the socket.

CAUTION: Do not heat zinc above 1200°F, or its bondingproperties will be lost.

The zinc temperature may be measured with a portablepyrometer or a Tempilstik. Remove all dross before pouring.Pour the zinc in one continuous stream until it reaches thebasket top and all wire ends are covered; there should be no“capping” of the socket.h. Remove serving. Remove the serving band from thesocket base; check to make certain that zinc has penetrated tothe socket base (see Figure B-1, View 9).i. Lubricate the rope. Apply wire rope lubricant to the rope atthe socket base and on any rope section where the originallubricant may have been removed.

B.2 Thermo-set Resin SocketingB.2.1 PROCEDURES

Before proceeding with a thermo-set resin-socketing pro-cedure, check manufacturer’s instructions carefully. Give par-ticular attention to selecting sockets that have been specifi-



cally designed for resin socketing. Follow the steps, outlinedbelow, or manufacturer’s directions, in the order given.

a. Seizing and cutting the rope. Follow rope manufacturer’sdirections for a particular rope size or construction withregard to the number, position, length of seizings, and theseizing-wire size. The seizing, located at the base of theinstalled fitting, must be positioned so that the ends of theembedded wires will be slightly below the level of the top ofthe fitting’s basket. The best means to cut the rope is with anabrasive wheel.b. Opening and brooming the strand wires. Before openingthe rope end, place a short temporary seizing directly abovethe seizing that represents the broom base. Temporary seizing

prevents brooming the wires the full length of the basket andalso prevents loss of lay in the strands and rope outside thesocket. Remove all seizing between the end of the rope and thetemporary seizing. Unlay the strands comprising the rope.Starting with the IWRC, or strand core, open each strand ofthe rope and broom or unlay the individual wires. When thebrooming is completed, wires should be distributed evenlywithin a cone so that they form an included angle of approxi-mately 60 degrees. Some types of sockets will require a some-what different brooming procedure, in which case themanufacturer’s instructions should be followed.

Note: (Note: A fiber core in the rope may be cut at the base of the seizing;some prefer to leave the core in. Consult the manufacturer’s instruction.)

Figure B-1—Zinc-poured Socketing Procedure

Source: Reprinted with permission of American Iron and Steel Institute, from Wire Rope User’s Manual, © 1981 American Iron and Steel Institute.



c. Cleaning the wires and fittings. Different types of resinwith different characteristics require varying degrees ofcleanliness. In some cases, merely using a soluble cleaningoil has been found effective. For one type of polyester resin,on which over 800 tensile tests on ropes in sizes 1⁄4 inch to 31⁄2 inch diameter were made without failure in the resin socketattachment, the cleaning procedure was as follows:

Clean wires thoroughly so as to obtain resin adhesion.Ultrasonic cleaning in recommended solvents such astrichloroethylene, 1-1-1 trichloroethane, or other non-flam-mable grease-cutting solvents is the preferred method ofcleaning the wires in accordance with OSHA Standards.Where ultrasonic cleaning is not available, brush or dip-cleaning in trichloroethane may be used, but fresh solventshould be used for each rope and fitting and discarded afteruse. After cleaning, the broom should be dried with cleancompressed air or in other suitable fashion before proceed-ing to the next step. The use of acid to etch the wires beforeresin socketing is unnecessary and not recommended. Also,the use of a flux on the wires before pouring resin should beavoided since this adversely affects resin bonding to thesteel wires. Since there is much variation in the properties ofdifferent resins, manufacturers’ instructions should be care-fully followed.

d. Closing rope ends and placing socket. Place rope in avertical position with the broom end up. Close and compactthe broom to permit insertion of the broomed end into thebase of the fitting. Slip the fitting on, removing any tempo-rary banding or seizing as required. Make certain that thebroomed wires are uniformly spaced in the basket, withwire ends slightly below the top edge of the basket, and thatthe axis of the rope and the fitting are aligned. Seal theannular space between the base of the fitting and the exitingrope to prevent leakage of the resin from the basket. A non-hardening butyl rubber-base sealant is satisfactory for thispurpose. Make sure that the sealant does not enter the baseof the socket so that the resin will be able to fill the com-plete depth of the socket basket.

e. Pouring the resin. Controlled heat-curing (no open flame)at a temperature range of 250°F to 300°F is recommended. Ifambient temperatures are less than 60°F, this is required!When controlled heat curing is not available and ambienttemperatures are not less than 60°F, the attachment should notbe disturbed, and tension should not be applied to the sock-eted assembly for at least 24 hours.

f. Lubrication after socket attachment. After the resin hascured, relubricate the wire rope at the base of the socket toreplace any lubricant that may have been removed during thecleaning operation.

g. Acceptable resin types. Commercially-available resinproperties vary considerably. Hence, it is important to refer tothe individual manufacturer’s instructions before using anyone type. General rules cannot, of course, be established.

When properly formulated, most thermoset resins areacceptable for socketing. These formulations, when mixed,form a pourable material which will harden at ambient tem-peratures, or upon the application of moderate heat. No openflame or molten metal hazards exist with resin socketingsince heat-curing, when necessary, requires a relatively lowtemperature (250°F to 300°F) obtainable by electric resis-tance heating.

Tests have demonstrated that satisfactory wire rope socket-ing performance can be obtained with resins having charac-teristics and properties as follows:

B.2.2 GENERAL DESCRIPTION

The resin shall be a liquid thermoset material that willharden after being mixed with the correct proportion of cata-lyst or curing agent. The following properties should benoted:

a. Properties of liquid (uncured) material. Resin and catalystare normally supplied in two separate containers. After thor-oughly mixing them together, the liquid can be poured intothe socket basket. Liquid resins and catalysts shall have thefollowing properties:

1. Viscosity of the resin-catalyst mixture. Viscosityshould be 30–40,000 CPS at 75°F immediately after mix-ing. Viscosity will increase at lower ambient temperatures,and resin may need warming prior to mixing in the cata-lyst if ambient temperatures drop below 40°F.2. Flash point. Both resin and catalyst shall have a mini-mum flash point of 100°F.3. Shelf life. Unmixed resin and catalyst shall have a min-imum of 1-year shelf life at 70°F.4. Pot life and cure time. After mixing, the resin-catalystblend shall be pourable for a minimum of 8 minutes at60°F and shall harden in 15 minutes. Heating of the resinin the socket to a maximum temperature of 250°F is per-missible to obtain full cure.

b. Properties of cured resin. The following should be notedconcerning properties of cured resin:

1. Socket performance. Resin shall exhibit sufficientbonding to solvent-washed wire in typical wire rope endfittings to develop the nominal strength of all types andgrades of rope. No slippage of wire is permissible whentesting resin-filled rope socket assemblies in tension. Aftertesting, however, some “seating” of the resin cone may beapparent and is acceptable.Resin adhesion to wires shall be capable of withstandingtensile-shock loading. 2. Compressive strength. The minimum allowable com-pressive strength for fully cured resin is 12,000 poundsper squaring.3. Shrinkage. Maximum allowable shrinkage is 2percent. To control shrinkage, an inert filler may be used



in the resin provided that viscosity requirements as spec-ified in B.2.2.a are met.4. Hardness. The desired hardness of the resin is in therange of Barcol 40–55.

B.2.3 RESIN-SOCKETING COMPOSITIONS

Manufacturer’s directions should be followed in handling,mixing, and pouring the resin composition.

B.2.4 PERFORMANCE OF CURED-RESIN SOCKETS

Poured-resin sockets may be moved after the resin hashardened. If one follows the ambient- or elevated-temperaturecure, as recommended by the manufacturer, resin sockets

should develop the nominal strength of the rope and have thecapability of withstanding shock loading to a degree suffi-cient to break the rope without cracking or breakage.Manufacturers of resin-socketing material shall be required totest these criteria before resin materials will be approved forrope-socketing use.

A FINAL NOTE OF CAUTION: The foregoing discussion is ageneralized description of but one of many commerciallyavailable thermo-set resins suitable for wire rope socketing.Characteristics of these products vary significantly and eachmust be handled differently. Thus, as noted earlier, specificinformation of any kind concerning any resin must beobtained from the individual manufacturer before setting up aresin-socketing procedure.


G00525 RP 2FP1, Design, Analysis, and Maintenance of Moorings forFloating Production Systems

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RP 2P, Analysis of Spread Mooring Systems for Floating Drilling Units

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